Well I've narrowed it down to the PSU, I have a 750W Silencer EPS12v Crossfire.
It really seems like enough,I have it right infront of me, it powers the MB FINE, it boots, but as soon as I plug that CPU power in it just fails, It MIGHT be the CPU. when I look at the cpu load or whatever on the meter with the MB its at high, tomorrow Im going to buy a 1000w PSU and im going to specify that i NEED it to run that.

Ill give you guys the specs for the PSU, For the record, its cool people like to help other people out, I really appreciate it. ( I also had power issues on another MB that kept frying the RAM? My friend says this is all my PSU ).

It has a 38AMPS max on it, I dont know if my CPU would take ALL THAT UP. but when I had it ALL plugged in, 295 gtx, CPU, RAM, HDD's and all, It booted and my 295 had the green light saying it had enough power. Could the CPU rail not be giving enough power?

Also, I can't boot up PERIOD, It starts and turns on and off in 1-2 second intervals. It really seems to either be the PSU can only power it for so long, (CPU) and then it shuts off, and tries again, or it could be the CPU is overheating? But I've never seen a CPU go from 0c to 90-100c ( whatever the tjmax is on the i7 ) in 2 seconds to 1 second.

ALSO, sorry for SOO many posts, I tried it without that extra power plugged in, just the mobo, works and boots up fine, doesn't shut off.
I'm almost sure its the PSU, but I just want some replies to reassure

Among other things, that behaviour sounds a little like something is being shorted, and the motherboard is shutting off in self-defense. It's not the only possibility, but it's one of them.

Stupid question, but you're positive that the 8-pin plug you're putting into the motherboard is the proper plug? And not an 8-pin PCI-E plug? They're supposed to be keyed differently, but with a little effort, they can be forced into the wrong socket, and they definitely have different pin-outs. Ditto for some other plugs - no USB headers plugged into firewire headers, or stuff like that? Power and reset wires on properly (or completely removed)?

Everythings completely removed, ALL of it but the CPU and the heatsink, also its a stock heatsink due to my old LG775 socket HS wont fit.

JUST the mobo and the CPU and PSU.

Like I said it just starts up, shuts down, starts up, shuts down, on its own after I press the power button. I really think it might be lack of power, and I'm sure i have the right connector because I've used this PSU for alot of setups, It used to fry my ram on my old MOBO and give me the C1 postcode, but now with the new mobo it wont boot period, or even post when the 8-pin's plugged into the CPU power.